1. Filed of the Invention
The present invention relates to a fan motor, particularly to a flat type fan motor with an improved ventilation structure.
2. Prior Art
Conventional micro processor units (hereinafter called MPU), which are mounted inside the casing of a thin electronic appliance such as a notebook type personal computer, have caused too much heat generation due to their large power consumption, and thus it has been imperative to provide MPU with a fan motor for cooling the same. For example, in Japanese Patent Examined Publication No. 7-54876 is disclosed a heat sink device which comprises a plurality of fins vertically provided on a base of the heat sink, said fins being arranged along a periphery of a fan motor so that at least an amount of air flow directed to one direction may differ from that directed to other directions, thereby allowing the air flow from the fan to strike effectively and directly on the fins so as to enhance the efficiency of radiation from the fins.
However, there have been various problems associated with such axial-flow fan motor for a thin electronic appliance, as disclosed in the prior art, due to the characteristic specifically required for the product, i.e., a limited height or thickness therefor.
Specifically, a less ventilation space between a casing of a thin electronic appliance and another casing which makes up an outer shape of a fan motor, has led to extremely inferior ventilation efficiency, because a substantial amount of air cannot be introduced into the inside of the casing. Further, due to an intake face being at right angles or orthogonal to an exhaust face so that air taken in the casing strikes a wall thereof, and thus the noise performance is inferior due to a ventilation passage being far from an ideal one. Furthermore, as an intake passage is inevitably determined by a fan motor when mounting the same to a thin electronic appliance, the cooling performance inside the whole appliance has become worse.
To eliminate the above-mentioned problems, it is, therefore, a primary object of the present invention to provide a fan motor with an improved inhaling structure.
It is another object of the present invention to provide a fan motor with improved ventilation efficiency and performance, improved cooling performance, as well as superior heat conductance.
To attain the above objects, there is proposed, from a first aspect of the invention, a fan motor to be mounted to an inside of a casing of a thin electronic appliance such as a personal computer, comprising: a fan for inhaling and exhausting air in a manner that an inhaling direction of air is perpendicular to an exhausting direction thereof; a drive unit for driving said fan; an outer housing member for accommodating said fan and drive unit, at least a part of said outer housing member being made from a material with good heat conductance, formed with a heat transferring portion thermally conductively connected to a heat source of the thin electronic appliance, said outer housing member having a first face and a second face which are opposite to said drive unit; and an intake hole provided in each face of said outer housing member, defining a first intake hole in the first face and a second intake hole in the second face, each said intake hole having a diameter for inhaling air in the vicinity of said first face and said second face;
wherein said fan includes a rotor and a plurality of fan blades formed on an outer peripheral side surface of the rotor, said rotor having a diameter defined by the outer peripheral side surface thereof, and
wherein said first and second intake holes supply air to said fan from respective opposite sides thereof, and have larger diameters than that of said rotor, while at least one of said first and second intake holes are formed to define a certain portion in which the air is drawn in from one side of said fan only.
According to a first aspect of the invention, as the intake hole of an arbitrary diameter is provided not only on a first side face of the housing member but also on a second side face thereof, a substantial amount of air can be taken in from both side faces of the housing member, thereby drastically improving ventilation efficiency, as compared to conventional ones. Further, by providing a second side face of the housing member with a second intake hole, the inhalation of air becomes possible even through a slightest clearance, even in the event that a substantial intake passage is not ensured at the first side face of the housing member when mounting a fan motor to the inside of the casing of an electronic appliance, whereby the cooling performance is improved. Furthermore, even though the inhaling direction of the fan is orthogonal to the exhaust direction thereof inside the outer housing member, the air taken in from one intake hole thereof will not strike on the wall thereof, but will be smoothly discharged toward the exhaust direction of the fan, together with air taken in from the other intake hole thereof. Accordingly, unlike conventional fan motors, the air taken in from the intake hole will not strike and damage the wall, whereby the inferior noise performance can be improved.
Specifically, as both of the intake holes are formed to have a larger diameter than the diameter of the rotor which is defined by the outer peripheral side surface thereof according to the present invention, the respective intake hole formed on each opposite face of the outer housing member allows the air to be drawn in from portions opposite to the fan blades located outside of the outer peripheral surface of the rotor in the center of the fan directly to the respective faces of the fan blades, without being hindered by the rotor. Further, due to a certain portion in which the air is drawn in from one side of said fan only, i.e., the presence of a portion which is free from counter flow of air, the flow of air toward the exhaust hole is first facilitated, and then such first flow of air is accompanied by subsequent flows of air such that a sufficient amount of air is drawn in from the respective surfaces of the remaining area, whereby air blasting efficiency can be drastically improved.
From a second aspect of the invention, there is proposed a fan motor to be mounted to an inside of a casing of a thin electronic appliance such as a personal computer, comprising: a fan for inhaling and exhausting air in a manner that an inhaling direction of air is perpendicular to an exhausting direction thereof; a drive unit for driving said fan; an outer housing member for accommodating said fan and drive unit, at least a part of said outer housing member being made from a material with good heat conductance, formed with a heat transferring portion thermally conductively connected to a heat source of the thin electronic appliance, said outer housing member having a first face and a second face which are opposite to said drive unit; and an intake hole provided in each face of said outer housing member, defining a first intake hole in the first face and a second intake hole in the second face, each said intake hole having a diameter for inhaling air in the vicinity of said first face and said second face;
wherein said fan includes a rotor and a plurality of fan blades formed on an outer peripheral side surface of the rotor, said rotor having a diameter defined by the outer peripheral side surface thereof, and
wherein said first and second intake holes supply air to said fan from respective opposite sides thereof, and have larger diameters than that of said rotor, while said first and second intake holes are formed to have a different opening area, respectively.
Accordingly, as each intake hole is formed to have a different opening area, there will inevitably be produced a certain portion which defines such different opening area in which the air is drawn in from one side of the fan only. In other words, due to the presence of a portion which is free from counter flow of air, the flow of air toward the exhaust hole is first facilitated, and then such first flow of air is accompanied by subsequent flows of air such that a sufficient amount of air is drawn in from the respective surfaces of the remaining area, whereby air blasting efficiency can be drastically improved.
From a third aspect of the invention, there is proposed a fan motor having the elements of said first or second aspect, which further comprises a radiator provided in the exhaust direction of the fan. With the structure, if heat from a certain heat source such as MPU reaches the radiator thermally conductibly connected with the heat source, air that has been efficiently taken in from both faces of the housing member will deprive the radiator of the heat thereof in the exhaust direction of the fan so speedily that the temperature rise of the heat source can be suppressed effectively. By providing the radiator in the exhaust direction of the fan in this way, the cooling effect of the heat source thermally conductibly connected with the radiator can be enhanced.
From a fourth aspect of the invention, there is proposed a fan motor having the elements of said first or second aspect, wherein the intake hole formed on the first face of said outer housing member is opposed to a face of a thin casing with a first space intervening therebetween, while the other intake hole formed in the second face thereof is opposed to a heat source with a second space intervening therebetween. With the structure, relatively cold air located in the vicinity of the first face of the outer housing member and relatively hot air located in the vicinity of the second face thereof are taken in simultaneously, which are smoothly discharged toward the exhaust direction of the fan while getting mixed.
From a fifth aspect of the invention, there is proposed a fan motor having the elements of the second aspect, wherein one of said intake holes has a larger area than the other, or vice versa. With the structure, if there is, for example, a heat generation body in the vicinity of the second face of the outer housing member, the second intake hole in the second side face of the housing member may be formed to have a larger opening area than the first intake hole in the first side face thereof. Thus, a more amount of air of relatively high temperature located in the vicinity of the second side face of the outer housing member is taken in than the air located in the vicinity of the first side face of the housing member, whereby the cooling effect relative to the heat generation body can be enhanced. Conversely, if the first intake hole in the first side face of the housing member is formed to have a larger opening area than the second intake hole in the second side face thereof, a more amount of air of relatively low temperature located in the vicinity of the first side face of the outer housing member is taken in, and thus if a radiator is provided in the exhaust direction of the fan, the cooling effect relative to the heat generation body thermally conductibly connected therewith can be enhanced. Accordingly, by varying the respective opening areas of the intake holes depending upon the surrounding structure of the fan motor, the cooling effect can be enhanced to the most desirable state.